// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_POWER_MONITOR_POWER_MONITOR_H_
#define BASE_POWER_MONITOR_POWER_MONITOR_H_

#include "base/base_export.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/observer_list_threadsafe.h"
#include "base/power_monitor/power_observer.h"

namespace base {

class PowerMonitorSource;

// A class used to monitor the power state change and notify the observers about
// the change event.
class BASE_EXPORT PowerMonitor {
public:
    // Takes ownership of |source|.
    explicit PowerMonitor(std::unique_ptr<PowerMonitorSource> source);
    ~PowerMonitor();

    // Get the process-wide PowerMonitor (if not present, returns NULL).
    static PowerMonitor* Get();

    // Add and remove an observer.
    // Can be called from any thread.
    // Must not be called from within a notification callback.
    void AddObserver(PowerObserver* observer);
    void RemoveObserver(PowerObserver* observer);

    // Is the computer currently on battery power.
    bool IsOnBatteryPower();

private:
    friend class PowerMonitorSource;

    PowerMonitorSource* Source();

    void NotifyPowerStateChange(bool battery_in_use);
    void NotifySuspend();
    void NotifyResume();

    scoped_refptr<ObserverListThreadSafe<PowerObserver>> observers_;
    std::unique_ptr<PowerMonitorSource> source_;

    DISALLOW_COPY_AND_ASSIGN(PowerMonitor);
};

} // namespace base

#endif // BASE_POWER_MONITOR_POWER_MONITOR_H_
